Musnad Ahmed: Hadith 4043

We were with the Messenger of Allah (ﷺ) in a cave and (the soorah) “By the winds (or angels or the Messengers of Allah) sent forth one after another" (al-Mursalat 77:1) was revealed to him. As we were learning it fresh from his lips, a snake appeared and he said: "Kill it.” We rushed to kill it but it got away from us. Then the Messenger of Allah (ﷺ) said: "It was protected from your evil as you were protected from its evil.”